Needle threading device assembled on sewing machines

ABSTRACT

A needle threading device for a sewing machine having its head closed laterally by a cover which includes a small plate supporting a needle threading hook having a longitudinal groove in its upper end, on its lower end a vertical wall insertable in a groove in the cover, a horizontal section adjoining the vertical wall which enables the operator to move the plate, two sections at right angles to each other on the lower end thereof, the first of which is horizontal and provides an edge to line up the threading hook with the needle eye of the machine and the second of which is vertical and provides support for the hook and a centering spring element, a reference element having a plane surface slanting with respect to the horizontal which may rest on the top of the needle bar of the machine and an oblique portion at its upper end to permit transversal oscillation of the hook lining up with the needle eye; a pin provided on the internal wall of the cover and engageable with the groove of the plate and a spring on the pin to constrain the plate against the internal wall of the cover.

United States Patent 1191 Bianchi NEEDLE THREADING DEVICE ASSEMBLED 0N SEWING MACHINES [75] Inventor: Nereo Bianchi, Pavia, Italy [73] Assignee: Necchi Societa per Azioni, Pavia,

Italy [22] Filed: June 14, 1973 [21] Appl. No.: 370,147

[30] Foreign Application Priority Data Primary Examiner-Richard J. Scanlan, Jr. Attorney, Agent, or Firm--Stevens, Davis, Miller Mosher [111 3,817,197 1 June 18, 1974 [5 7] ABSTRACT A needle threading device for a sewing machine having its head closed laterally by a cover which includes a small plate supporting a needle threading hook having a longitudinal groove in its upper end, on its lower end a vertical wall insertable in a groove in the cover, a horizontal section adjoining the vertical wall which enables the operator to move the plate, two sections at right angles to each other on the lower end thereof. the first of which is horizontal and provides an edge to line up the threading hook with the needle eye of the machine and the second of which is vertical and provides support for the hook and a centering spring element, a reference element having a plane surface slanting with respect to the horizontal which may rest on the top of the needle bar of the machine and an oblique portion at its upper end to permit transversal oscillation of the hook lining up with the needle eye; a pin provided on the internal wall of the cover and engageable with the groove of the plate and a spring on the pin to constrain the plate against the internal wall of the cover.

7 Claims, 6 Drawing Figures PATENTEDJun 1 8 an mm E.

The present invention relates to a needle threading device assembled on sewing machines the head of which is closed laterally by a cover.

Some needle threading devices already known in the art have a complex and bulky structure, devised to secure the correct positioning of the thread catching hook with respect to the needle eye on passing from the idle position of the device to the working position.

Other devices known in the art, less complex than the former ones, require, before their use, a preliminary maneuver from the operator, i.e., the opening of the sewing machine head cover because the needle threader is wholly located within said head and cannot be operated from the exterior. Many other devices known in the art require, moreover, for their working, a careful positioning in advance of the needle bar and, therefore, of the needle eye.

The purpose of the present invention is to create a simple needle threading device both as regards construction and working which eliminates the inconveniences mentioned above.

The technical problem to be solved in order to obtain the expressed purpose was to reduce to a minimum the elements making up said device and to equip the device with suitable means for its working so that it may be transferred from a rest position, in which it is hidden into the sewing machine head, to a working position in which its threading hook is set automatically in line with the needle eye.

The solution of the above technical problem is chap acterized by the fact that the device consists of a small plate bearing the needle threading hook constrained to the lateral cover of the sewing machine head in such a way as to make some linear displacements in contact with the internal surface of the cover and pendular oscillations within two vertical orthogonal planes. The displacements and oscillations are apt to transfer the threading hook from a rest position to a position in which it is in line with the needle eye and, subsequently, it is apt to make the movement for threading the thread through said needle eye.

Further characteristics and advantages will be evidenced by the description of a preferred embodiment of the device object of the present invention and in the drawings attached hereto, in which:

FIG. I. is a partial front view, cross-section, of a sewing machine head containing the device of the invention;

FIG. 2 is a lateral view of the head and the device of FIG. l;

FIG. 3 shows a detailed perspective view of the device of FIG. ll;

FIGS. 4 and 5 show, schematically, two working conditions of the device of FIG. 1, and finally FIG. 6 shows a detailed perspective view of the de vice of FIG. l in a rest position.

In FIG. 1, there is indicated sewing machine head 10 with the end of the horizontal arm 11 within which the main shaft 12 is located, which arm is supported by bushing 13.

Moreover, there is indicated the conventional handcrank 14 with the connecting-rod l5 apt to transmit the vertical alternating movement to the needle bar 16.

The connection between connecting rod 15 and needle bar i6 is made by means of an articulation l7 allowing the needle bar in to incline with respect to the vertical line when the machine is making zigzag stitches.

The needle bar support 18 receives in a usual way the unidimensional impulses for the zigzag sewing from a control rod not shown in the drawings and oscillates by means of a carriage spring 19 connecting said support 18, at its oscillation center consisting of the point of attachrnent of said spring, to boss 20 provided on the sewing machine frame.

Screw 21 is the fastening means for spring 19 to boss 20. In FIGS. 1 and 2 there also is indicated, in a general way, thread take-up device 22 actuated in a known way by the rotation of the main shaft 12 through handcrank 14, connecting rod 15, presser bar 23 and presser foot 24.

According to the features of the present invention, the sewing machine head 10 is closed laterally by a cover 25 having the shape of a plate on the exterior of which are fixed the knob 26 for regulating the upper thread tension and the knob 27 for regulating the presser bar.

On the interior surface of cover 25 a pin 28 is fixed, which is provided with a head 29.

The needle threading device consists of a small plate 30 having a lengthened shape with a lengthwise groove 31 at its top (FIG. 2). This groove is engaged by pin 28 about which plate 30 can pivot and is pushed against the internal wall of cover 25 by one end of a spiral spring 32 having a conical shape. The other end of the spring 32 rests against the head 29 of pin 28.

Small plate 30 (FIG. 3) has, in its lower section, a vertical wall 33 having connected thereto a rectangularly shaped horizontal plate 34 whose task will be illustrated hereinafter.

A further extension of small plate 30 consists of the two sections 35 and 36 forming a right angle between them. The first section 35 has an edge 37 whose task will be explained hereinafter. 0n the second vertical section 36 are fixed in a known way hook 38 for the thread and two elastic springs 39 and 40 apt to engage the ending wall of needle 4-1 and secure the exact positioning of hook 38 to the needle eye 42. Small plate 30 is provided, on its top, by a section 43 slanting with respect to the remaining section and a reference element 44 ending in a little plane 45, slanting from the horizontal. The reason for these arrangements will be made clear by the following description of the working of the device of the present invention.

In FIGS. 1 and 2 the needle threading device is shown in its rest position.

Spring 32 forces small plate 30 of the device against the internal wall of cover 25. Small plate 30 is prevented from rotating about pin 28 owing to the fact that its vertical wall 33 is inserted in a slot provided on the lower end of the cover itself.

When the operator wants to thread the needle by means of the device described, he exerts pressure with his finger on section 34 of plate 30 which, overcoming the friction created by spring 32, moves downwards according to the connection formed by the coupling be tween pin 28 and groove 31.

As long as the portion of groove 31 that is engaged by pin 28 is below the slanting section 43, small plate 30 moves downwardly in a parallel relationship (FIG.

1) with needle bar 16 positioned vertically in its central point with respect to zigzag sewing.

When, with the further lowering of small plate 30, pin 28 engages the upper part of groove 31 located in the slanting section 43 of small plate 30, the residual lower section of plate 30 obviously takes a slanting position towards the needle 41 (FIG. 4), thus lining up hook 38 with needle eye 42.

The slanting of section 43 with respect to the residual section of small plate 30 is such as to bring hook 38 in line with the needle eye 42, so that the threading of the hook may take place through a simple oscillation of small plate 30 about pin 28. The downward displacement of small plate 30 stops when section 45 of reference element 44 rests on the upper part of needle bar 16, which the operator already has brought to nearly its top dead center position.

One advantage of the device of the present invention with respect to some types known in the art consists of the fact that no special care is required for positioning the needle bar 16 in its highest position. The needle eye can be threaded by hook 38 in a rather wide range of positions near the top dead center position of the needle bar.

It is evident that the length of this range, after carrying out a careful regulation of the device, may be considered equal to the length of groove 31 with respect to the slanting section 43 of plate 30.

When hook 38 is placed at the same height as the needle eye 42 and lined up between presser bar 23 and needle 41, the operator makes small plate 30 oscillate about pin 28, taking care that edge 37 of the horizontal section 35 touches the needle slightly, until the needle stops between small springs 39 and 40, as shown in FIG. 3.. Pursuing the rotation of small plate 30, hook 38 enters the needle eye 42 in order to take up the thread and pass it through the needle eye when the operator makes said small plate 30 oscillate in the opposite direction. A further advantage of the present invention is that by a simple contrivance the needle threading device is adapted to operate in any position of the needle in a transversal direction to the stitching line, i.e., in any position possibly taken by the needle bar when performing zigzag sewing.

For this purpose, section 45 of reference element 44 fixed to the upper part of small plate 30 is somewhat slanted with respect to the horizontal.

Small plate 30 has, besides the possibility of making oscillations about pin 28 relative to the actual threading operation, also the possibility of making, contrary to the action of spring 32, oscillations in parallel to the transversal displacements of the needle when making zigzag stitches. As is shown in FIGS. 4 and 5, this further capability allows hook 38 of the threading device to follow the needle eye, which may be displaced with respect to its central position indicated in FIGS. 4 and by the A-A dash and point line. The hook, however, transversally oscillating with small plate 30 (FIG. 5), moves up to a higher position owing to the position of the rotation center of the small plate, while needle 41 and its bar 16, whose rotation center lies practically on the extension of their axis during their transversal oscillations, make a portion of them, which may be the needle eye 42 or the upper section of the needle bar 16, perform transversal oscillations substantially equal as 4 to height.

Thus, for instance, suppose the needle is in the position of maximum zigzag to the right (FIG. 5), with the needle bar at its top dead center. When section 45 comes down, following small plate 30, it rests on the needle bar top with its higher portion. That means a greater excursion downwards of plate 30, such as to compensate its upward displacement during the subsequent transversal lining up oscillation of the hook with respect to the needle eye. Due to this, the needle eye and the hook remain at the same height during the whole width of the transversal excursion of the needle.

Threading is thus accomplished in any sewing condition.

What is claimed is:

1. In a sewing machine having a lateral head cover a needle threading device comprising a small plate supporting the needle threading hook and means to constrain said plate to said cover so as to make linear displacements in contact with the internal surface of said cover and pendular oscillations within two vertical orthogonal planes, said displacements and oscillations being apt to transfer the threading hook from a rest position to a position in which it is lined up with the needle eye and performs the threading movement through said needle eye.

2. The sewing machine according to claim 1, wherein said means include a pin provided on the internal wall of said cover and a spiral spring having a conical shape provided on said pin, said small plate having on its top a longitudinal groove engageable with said pin and being constrained against the internal wall of the cover by said spring.

3. The sewing machine according to claim 2 in which said small plate has, on its lower section, a vertical wall insertable in a special groove provided in the lower section of the cover and in cooperation with said spring fixes the small plate to the cover in the rest position.

4. The sewing machine according to claim 3, in which said small plate has a horizontal section adjoining said vertical wall, movable by the operator so as to bring said small plate from a rest position to a working position.

5. The sewing machine according to claim 1, in which said small plate is terminated in its lower portion by two level sections at right angles with each other, the first is horizontal and provides an edge to line up the threading hook with the needle eye, the second is vertical and provides support for said hook anda centering spring element.

6. The sewing machine according to claim 1, including a reference element fixed to said small plate and having a plane surface slanting with respect to the hori zontal apt to rest on the needle bar top in order to determine the height position of the hook with respect to the needle eye.

7. The sewing machine according to claim I, in which said small plate has an oblique portion at its upper end permitting transversal oscillation of the hook lining up with the needle eye, when at the end of the plates downward displacement said oblique portion rests on the lateral wall of the cover. 

1. In a sewing machine having a lateral head cover a needle threading device comprising a small plate supporting the needle threading hook and means to constrain said plate to said cover so as to make linear displacements in contact with the internal surface of said cover and pendular oscillations within two vertical orthogonal planes, said displacements and oscillations being apt to transfer the threading hook from a rest position to a position in which it is lined up with the needle eye and performs the threading movement through said needle eye.
 2. The sewing machine according to claim 1, wherein said means include a pin provided on the internal wall of said cover and a spiral spring having a conical shape provided on said pin, said small plate having on its top a longitudinal groove engageable with said pin and being constrained against the internal wall of the cover by said spring.
 3. The sewing machine according to claim 2 in which said small plate has, on its lower section, a vertical wall insertable in a special groove provided in the lower section of the cover and in cooperation with said spring fixes the small plate to the cover in the rest position.
 4. The sewing machine according to claim 3, in which said small plate has a horizontal section adjoining said vertical wall, movable by the operator so as to bring said small plate from a rest position to a working position.
 5. The sewing machine according to claim 1, in which said small plate is terminated in its lower portion by two level sections at right angles with each other, the first is horizontal and provides an edge to line up the threading hook with the needle eye, the second is vertical and provides support for said hook and a centering spring element.
 6. The sewing machine according to claim 1, including a reference element fixed to said small plate and having a plane surface slanting with respect to the horizontal apt to rest on the needle bar top in order to determine the height position of the hook with respect to the needle eye.
 7. The sewing machine according to claim 1, in which said small plate has an oblique portion at its upper end permitting transversal oscillation of the hook lining up with the needle eye, when at the end of the plate''s downward displacement said oblique portion rests on the lateral wall of the cover. 